How can I update jenkins plugins from the terminal?

You can update plugins list with this command line

curl -s -L http://updates.jenkins-ci.org/update-center.json | sed '1d;$d' | curl -s -X POST -H 'Accept: application/json' -d @- http://localhost:8080/updateCenter/byId/default/postBack

You can actually install plugins from the computer terminal (rather than the Jenkins terminal).

1. Download the plugin from the plugin site (http://updates.jenkins-ci.org/download/plugins)
2. Copy that plugin into the $JENKINS_HOME/plugins directory
3. At that point either start Jenkins or call the reload settings service (http://yourservername:8080/jenkins/reload)

This will enable the plugin in Jenkins and assuming that Jenkins is started.

cd $JENKINS_HOME/plugins
curl -O http://updates.jenkins-ci.org/download/plugins/cobertura.hpi
curl http://yourservername:8080/reload

A simple but working way is first to list all installed plugins, look for updates and install them.

java -jar /root/jenkins-cli.jar -s http://127.0.0.1:8080/ list-plugins

Each plugin which has an update available, has the new version in brackets at the end. So you can grep for those:

java -jar /root/jenkins-cli.jar -s http://127.0.0.1:8080/ list-plugins | grep -e ')$' | awk '{ print $1 }'

If you call install-plugin with the plugin name, it is automatically upgraded to the latest version.

Finally you have to restart jenkins.

Putting it all together (can be placed in a shell script):

UPDATE_LIST=$( java -jar /root/jenkins-cli.jar -s http://127.0.0.1:8080/ list-plugins | grep -e ')$' | awk '{ print $1 }' ); 
if [ ! -z "${UPDATE_LIST}" ]; then 
    echo Updating Jenkins Plugins: ${UPDATE_LIST}; 
    java -jar /root/jenkins-cli.jar -s http://127.0.0.1:8080/ install-plugin ${UPDATE_LIST};
    java -jar /root/jenkins-cli.jar -s http://127.0.0.1:8080/ safe-restart;
fi

Here is how you can deploy Jenkins CI plugins using Ansible, which of course is used from the terminal. This code is a part of roles/jenkins_ci/tasks/main.yaml:

- name: Plugins
  with_items:                             # PLUGIN NAME
  - name: checkstyle                      # Checkstyle
  - name: dashboard-view                  # Dashboard View
  - name: dependency-check-jenkins-plugin # OWASP Dependency Check
  - name: depgraph-view                   # Dependency Graph View
  - name: deploy                          # Deploy
  - name: emotional-jenkins-plugin        # Emotional Jenkins
  - name: monitoring                      # Monitoring
  - name: publish-over-ssh                # Publish Over SSH
  - name: shelve-project-plugin           # Shelve Project
  - name: token-macro                     # Token Macro
  - name: zapper                          # OWASP Zed Attack Proxy (ZAP)
  sudo: yes
  get_url: dest="{{ jenkins_home }}/plugins/{{ item.name | mandatory }}.jpi"
           url="https://updates.jenkins-ci.org/latest/{{ item.name }}.hpi"
           owner=jenkins group=jenkins mode=0644
  notify: Restart Jenkins

This is a part of a more complete example that you can find at: https://github.com/sakaal/service_platform_ansible/blob/master/roles/jenkins_ci/tasks/main.yaml

Feel free to adapt it to your needs.